Construction and earthmoving equipment, as well as many other types of machines, are commonly used in a wide variety of applications. Generally, a machine is powered by an internal combustion engine such as a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of engine. These engines include a piston moving in a cylinder with accompanying combustion, the piston being retained in a cylinder block. A connecting rod connects the piston to a crankshaft, where a first end portion of the connecting rod is assembled to the piston and a second end portion of the connecting rod is assembled to a crankpin associated with the crankshaft. As an engine increases its speed, the crankshaft rotates at an increased speed, and the rotational movement of the crankshaft is converted to linear movement of the piston through the connecting rod. An oil film associated with the crankpin and an inner diameter surface of the second end portion experiences shearing as the crankpin rotates within the second end portion.
When an engine operates at high speeds, the shearing velocity of the oil film increases and may become excessive. The excessive shearing velocity of the oil film may result in less than desirable engine durability. As shearing velocity becomes excessive, the oil film becomes hotter which may cause the oil film viscosity to reduce and subsequently the oil film to become thinner. This may lead to contact between the inner diameter surface of the second end portion and the crankpin and increased wear of the second end portion.
One system for improving engine performance and durability is described in U.S. Patent Application Publication No. 2005/0238269 (the '269 publication) to Endoh et al., published on Oct. 27, 2005. The '269 publication describes a floating bearing formed as a single piece and disposed between a crankpin of a crankshaft and a big end of a connecting rod, with oil films formed on a side of the crankpin and on a side of the big end. The floating bearing acts in such a manner as to reduce friction loss of the crankshaft and wearing of the crankpin and the big end of the connecting rod. Specifically, during rotation of the crankpin relative to the big end, the floating bearing rotates at a velocity which is approximately one-half of the rotational velocity of the crankpin, such that friction between the floating bearing and the big end, and between the floating bearing and the crankpin, is smaller as compared to a crankpin rotating relative to just the big end of the connecting rod. Therefore, when the floating bearing is applied to an engine, the engine has increased durability and can operate at a high speed.
Although the floating bearing system of the '269 publication may reduce friction loss of the crankshaft and wear of the crankpin and the big end of the connecting rod, it may have limitations. The floating bearing is described as simply cylindrical in nature, and therefore, not likely to attain an efficient rate of relative rotation.
The bearing system of the present disclosure is directed towards improvements in the existing technology.